To Agassiz himself the expedition was of the deepest interest. Glacial phenomena had, as we have seen, met him at every turn since his arrival in the United States, but nowhere had he found them in greater distinctness than on the shores of Lake Superior. As the evidence accumulated about him, he became more than ever satisfied that the power which had modeled and grooved the rocks all over the country, and clothed it with a sheet of loose material reaching to the sea, must have been the same which had left like traces in Europe. In a continent of wide plains and unbroken surfaces, and, therefore, with few centres of glacial action, the phenomena were more widely and uniformly scattered than in Europe. But their special details, down to the closest minutiae, were the same, while their definite circumscription and evenness of distribution forbade the idea of currents or floods as the moving cause. Here, as elsewhere, Agassiz recognized at once the comprehensive scope of the phenomena. The whole history reconstructed itself in his mind, to the time when a sheet of ice clothed the land, reaching the Atlantic sea-board, as it now does the coast of Spitzbergen and the Arctic shores. He made also a careful survey of the local geology of Lake Superior, and especially of the system of dykes, by the action of which he found that its bed had been excavated, and the outline of its shores determined. But perhaps the inhabitants of the lake itself occupied him even more than its conformation or its surrounding features. Not only for its own novelty and variety, but for its bearing on the geographical distribution of animals, the fauna of this great sheet of fresh water interested him deeply. On this journey he saw at Niagara for the first time a living gar-pike, the only representative among modern fishes of the fossil type of Lepidosteus. From this type he had learned more perhaps than from any other, of the relations between the past and the present fishes. When a student of nineteen years of age, his first sight of a stuffed skin of a gar-pike in the Museum of Carlsruhe told him that it stood alone among living fishes. Its true alliance with the Lepidosteus of the early geological ages became clear to him only later in his study of the fossil fishes. He then detected the reptilian character of the type, and saw that from the articulation of the vertebrae the head must have moved more freely on the trunk than that of any fish of our days. To his great delight, when the first living specimen of the gar-pike, or modern Lepidosteus, was brought to him, it moved its head to the right and left and upward, as a Saurian does and as no other fish can.